Competence of corncob (Zea mays L.) powder with HCl activation as adsorbent to purify waste cooking oil: Reference in the batch adsorption process

The quality of cooking oil needs to be maintained. To purify used cooking oil, an adsorption process involving adsorbents is required. In this study, a 100 mL sample of used cooking oil was taken. The oil was then left to settle for 20 min before measuring the initial turbidity level with a turbidimeter. In manufacturing adsorbents from corncob powder with sizes 50 mesh, 70 mesh, and 100 mesh, each weighed as much as 25 g, mixed with 150 ml of 0.1 M hydrochloric acid for 3 h, and dried in the oven. Each size of adsorbent was weighed as much as 2 g, 3 g, and 4 g. The adsorption process was done by mixing oil with corncob adsorbent in a beaker glass. Every 20 min, turbidity was measured using a turbidimeter for 5 h. Based on the turbidimeter results, an adsorbent size of 100 mesh with a mass of 4 g has an adsorption capacity of 12,728 mg/g with percentage reduction of turbidity of 94.5%. Based on the Scanning Electron Microscope-Energy Dispersive X-ray results, the surface of the HCl-activated adsorbent has pores with a distance of 10 µm, and the adsorbent contains carbon, oxygen, silica, and copper compounds. According to the Fourier Transform Infrared results, there is a change in functional groups, Brunauer-Emmett-Teller results show a change in surface area, and Gas Chromatography-Mass Spectrophotometry results show a decrease in free fatty acids in used cooking oil after purification.